From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Masahiro Yamada <masahiroy@kernel.org>,
Nicolas Schier <nicolas@fjasle.eu>,
Michal Marek <michal.lkml@markovi.net>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
llvm@lists.linux.dev
Subject: [PATCH v2 15/26] kbuild: record symbol versions in *.cmd files
Date: Sun, 1 May 2022 17:40:21 +0900 [thread overview]
Message-ID: <20220501084032.1025918-16-masahiroy@kernel.org> (raw)
In-Reply-To: <20220501084032.1025918-1-masahiroy@kernel.org>
When CONFIG_MODVERSIONS=y, the output from genksyms is saved in
separate *.symversions files, and will be used much later when
CONFIG_LTO_CLANG=y because it is impossible to update LLVM bit code
here.
This approach is not robust because:
- *.symversions may or may not exist. If *.symversions does not
exist, we never know if it is missing for legitimate reason
(i.e. no EXPORT_SYMBOL) or something bad has happened (for
example, the user accidentally deleted it). Once it occurs,
it is not self-healing because *.symversions is generated
as a side effect.
- stale (i.e. invalid) *.symversions might be picked up if an
object is generated in a non-ordinary way, and corresponding
*.symversions (, which was generated by old builds) just happen
to exist.
A more robust approach is to save symbol versions in *.cmd files
because:
- *.cmd always exists (if the object is generated by if_changed
rule or friends). Even if the user accidentally deletes it,
it will be regenerated in the next build.
- *.cmd is always re-generated when the object is updated. This
avoid stale version information being picked up.
I will remove *.symversions later.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
---
Changes in v2:
- Fix CONFIG_MODULE_REL_CRCS=y case
scripts/Makefile.build | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f6a506318795..a1023868775f 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -171,10 +171,17 @@ ifdef CONFIG_MODVERSIONS
# Generate .o.symversions files for each .o with exported symbols, and link these
# to the kernel and/or modules at the end.
+
+genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).*
+genksyms_format_normal := __crc_\(.*\) = \(.*\);
+genksyms_format := $(if $(CONFIG_MODULE_REL_CRCS),$(genksyms_format_rel_crc),$(genksyms_format_normal))
+
gen_symversions = \
if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
> $@.symversions; \
+ sed -n 's/$(genksyms_format)/$(pound)SYMVER \1 \2/p' $@.symversions \
+ >> $(dot-target).cmd; \
else \
rm -f $@.symversions; \
fi
--
2.32.0
next prev parent reply other threads:[~2022-05-01 8:44 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 8:40 [PATCH v2 00/26] kbuild: yet another series of cleanups (modpost and LTO) Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 01/26] modpost: use bool type where appropriate Masahiro Yamada
2022-05-03 21:43 ` Nick Desaulniers
2022-05-04 5:47 ` Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 02/26] modpost: change mod->gpl_compatible to bool type Masahiro Yamada
2022-05-03 21:45 ` Nick Desaulniers
2022-05-01 8:40 ` [PATCH v2 03/26] modpost: import include/linux/list.h Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 04/26] modpost: traverse modules in order Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 05/26] modpost: add sym_add_unresolved() helper Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 06/26] modpost: traverse unresolved symbols in order Masahiro Yamada
2022-05-03 21:49 ` Nick Desaulniers
2022-05-01 8:40 ` [PATCH v2 07/26] modpost: use doubly linked list for dump_lists Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 08/26] modpost: traverse the namespace_list in order Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 09/26] modpost: dump Module.symvers in the same order of modules.order Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 10/26] modpost: move static EXPORT_SYMBOL check to check_exports() Masahiro Yamada
2022-05-03 21:54 ` Nick Desaulniers
2022-05-01 8:40 ` [PATCH v2 11/26] modpost: make multiple export error Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 12/26] modpost: make sym_add_exported() always allocate a new symbol Masahiro Yamada
2022-05-03 21:56 ` Nick Desaulniers
2022-05-01 8:40 ` [PATCH v2 13/26] modpost: split new_symbol() to symbol allocation and hash table addition Masahiro Yamada
2022-05-03 22:00 ` Nick Desaulniers
2022-05-01 8:40 ` [PATCH v2 14/26] modpost: mitigate false-negatives for static EXPORT_SYMBOL checks Masahiro Yamada
2022-05-01 8:40 ` Masahiro Yamada [this message]
2022-05-01 8:40 ` [PATCH v2 16/26] kbuild: generate a list of objects in vmlinux Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 17/26] modpost: extract symbol versions from *.cmd files Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 18/26] modpost: generate linker script to collect symbol versions Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 19/26] kbuild: embed symbol versions at final link of vmlinux or modules Masahiro Yamada
2022-05-03 2:55 ` Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 20/26] kbuild: stop merging *.symversions Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 21/26] genksyms: adjust the output format for .cmd files Masahiro Yamada
2022-05-04 20:22 ` Nicolas Schier
2022-05-05 13:47 ` Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 22/26] kbuild: do not create *.prelink.o for Clang LTO or IBT Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 23/26] kbuild: make built-in.a rule robust against too long argument error Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 24/26] kbuild: make *.mod " Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 25/26] modpost: simplify the ->is_static initialization Masahiro Yamada
2022-05-01 8:40 ` [PATCH v2 26/26] modpost: use hlist for hash table implementation Masahiro Yamada
2022-05-01 12:23 ` [PATCH v2 00/26] kbuild: yet another series of cleanups (modpost and LTO) Masahiro Yamada
2022-05-05 6:55 ` Masahiro Yamada
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